What does an arrow mean? A reaction takes placed if physical change takes place no change takes place and I chemical reaction.
An arrow in a chemical equation typically represents a reaction. It shows the direction in which the reactants (substances before the arrow) are transformed into products (substances after the arrow). The arrow indicates the chemical change or reaction that occurs under specific conditions, such as the addition of heat or the presence of a catalyst.
However, it's unclear what you mean by "A reaction takes placed if physical change takes place no change takes place and I chemical reaction." Could you please clarify your statement?